The invention lies in the field of mechanics, in particular of mechanical engineering and precision technology. It concerns those mechanical problems which arise on inserting a flexible, elongate body into an opening or sheath, due to its tendency to buckle. To buckle in the context of the present invention is also to be understood as to abruptly bend, and could also be described as kinking in a two-dimensional manner, in accordance with the German word “knicken”.
Such flexible, elongate bodies may for example be cables, wires, threads, flexible tubings or a combination of such elements, which are typically to be inserted into sheaths or openings, tubes, hoses or generally cavities. Such an elongate body may also be a second sheath which is inserted into a first sheath or is to be held in a stationary manner with respect to this. If a resistance against a further pushing movement results when pushing such bodies, then the body must be prevented from buckling, in order to permit a further push movement, or corresponding radial deflection movements must be limited.
As a whole, amongst other things, it is case of designing the handling such that it is secure as possible. Thereby, it is advantageous if on introduction, a certain buckling angle is not exceeded and a certain bending radius is not fallen short of.
One application of the invention for example results on introducing a mechanical pipe cleaning device into a pipe conduit system, wherein the cleaning device is inserted with a flexible shaft.
Typically, such problems also result in medical technology, if for example a canulla or a catheter is to be inserted into a body opening, a lumen of the body or an artificial lumen
Typical such situations are for example evident from the international patent application WO 02/43791 A1. There, it is described that an intravascular pump is introduced into a sheath, in order finally to be inserted it into a blood vessel of a human body. A further push movement takes place, also after the pump has passed the actual sheath region.
Since such pumps are to be pushed through a blood vessel over lengths of a few tens of centimeters within the body, one must reckon with a certain push resistance which renders necessary a certain push force on inserting. In particular with self-openable or self-expandable pumps heads, one is to reckon with an increased push resistance on account of the occurring restoring forces of the folded or compressed pump head. This is particularly due to the fact that because with such pumps, a flexible shaft which is envisaged for high rotation speeds and a long service life and which is sensitive to buckling runs within a catheter to be pushed, it must be ensured that the necessary push force may be applied onto the catheter without this buckling out or deflecting in another manner.